The invention relates to the control of occupant protection measures of a precrash safety system in a motor vehicle.
Precrash safety systems are safety systems that implement one or more occupant protection measures in order to better protect the occupants in the event of an accident, when a safety-critical situation, in which it is likely that an accident might follow, is detected. Such occupant protection measures are most likely reversible occupant protection measures—that is, measures that can be reset again after the hazardous situation has ended and can be retriggered again in the event of a new hazardous situation. However, even non-reversible occupant protection measures can be triggered by a precrash safety system.
A typical example of reversible occupant protection measures of a precrash safety system is the seat belt tensioning by means of an electric motor-operated seat belt tensioner (for example, an electric motor-operated seat belt retractor). In contrast to a non-reversible pyrotechnic seat belt tensioner, the force in an electric motor-operated seat belt tensioner is generally significantly less. When the seat belt is tightened, the belt slack is taken out, so that the safety belt better protects the vehicle occupants in the event of an accident. The documents DE 101 21 386 C1, DE 10 2005 038 226 A1, DE 100 05 010 A1 and WO 01/96152 A1 describe some examples of precrash safety systems with belt tensioning.
In order to actuate an occupant protection measure, such as a belt tensioner, a precrash safety system typically evaluates the momentary state of the driving dynamics of the motor vehicle. For example, the precrash safety system can check whether the vehicle is in an oversteering, understeering or even emergency braking situation. In addition, signals from the environment sensors can be evaluated for actuation purposes. For example, the data determined by use of radar can be evaluated in order to predict a collision.
When triggering situations relating to the driving dynamics occur in rapid succession—for example, oversteering in a left-hand curve, driving straight ahead for a short distance, then oversteering in a right-hand curve—a conventional precrash safety system will trigger the belt tensioner every time. This multiple triggering of the belt tensioner—that is, this repeated tensioning operation—in a short period of time may cause the occupants to be annoyed—especially when driving in the top speed range. Moreover, repeated tensioning in a short period of time is not necessary from the viewpoint of occupant safety, because the belt slack is already taken out during the first tensioning operation, and no significant amount of belt slack will form during the driving maneuvers that follow shortly thereafter.
An additional drawback with the conventional precrash safety systems is the lack of scalability to additional input and/or output variables. Precrash safety systems can be expanded on the input side, for example, in the future in such a way that they process the events that are reported by camera-based systems that look ahead. In addition, it would be advantageous if such systems could be easily expanded on the output side to include, in addition to the belt tensioning, other occupant protection measures, such as closing the windows and closing—if present—the sliding roof as well as moving the seat headrest into the upright position.
The object of the present invention is to eliminate the drawbacks of the conventional precrash safety systems.
A first aspect of the invention relates to a method for controlling at least one reversible occupant protection measure of a motor vehicle precrash safety system, in particular a reversible belt tensioner. Not only the control of one or more additional reversible occupant protection measures, but also the control of an additional non-reversible occupant protection measure is contemplated. According to the method, a plurality of input signals are received, wherein the input signals indicate a potential risk of an accident. The input signals are typically sensor signals, from which a critical driving state (for example, oversteering, understeering, emergency braking) or a critical surrounding situation (short distance to collision derived from radar measurements) can be detected. The input signals are mapped onto precrash severity indicators. Preferably, each input signal is assigned a precrash severity indicator. Each precrash severity indicator indicates an expected probability and/or severity of the accident. In determining the precrash severity indicator as a function of an input signal, which is not a binary signal, a threshold value comparison is typically also performed. The precrash severity indicators have varying priorities and are set as a function of the input signals.
According to the method, the precrash severity indicators are preferably also filtered, a feature that is also referred to below as “temporal debouncing”. The filtering is carried out in such a manner that upon occurrence of a precrash severity indicator, a subsequent precrash severity indicator is suppressed for a period of time (that is, temporarily). In this way it is possible to avoid unnecessary multiple triggering actions for a short period of time. Preferably, only one precrash severity indicator having an equally high or lower priority than the priority of the previous precrash severity indicator is suppressed, while a precrash severity indicator having a higher priority than the priority of the previous precrash severity indicator is not suppressed. This feature makes it possible for a precrash severity indicator having a correspondingly high priority to be able, nevertheless, to trigger an occupant protection measure of the precrash safety system.
Then the at least one reversible occupant protection measure, such as belt tensioning, is triggered as a function of the filtered precrash severity indicators. At the same time each filtered precrash severity indicator or each filtered precrash severity indicator from a subset of the filtered precrash severity indicators is assigned one or more actuators of the precrash safety system—for example, a defined force characteristic of the electric motor-operated belt tensioner, the window closing mechanism and/or the seat adjuster (moving the seat headrest into the upright position).
The method according to the invention provides that the individual input data from the various sensor systems—for example, from the internal (that is, relating to the driving dynamics) and from the external (that is, environment sensing) sensor systems—are coordinated and prioritized in such a way that a situation, in which unnecessary multiple triggering actions occur, does not arise.
Owing to the filtering of the precrash severity indicators, whereby the subsequent precrash severity indicators are suppressed, the brief safety-critical events that take place in succession one after the other, such as emergency braking followed by oversteering, do not result in an unnecessary multiple triggering of the occupant protection measure, such as the belt tensioning.
Furthermore, the prioritizing of the precrash severity indicators permits that not all of the subsequent precrash severity indicators are suppressed within a time frame, but rather correspondingly high-ranking precrash severity indicators are not suppressed and, thus, can still result in the triggering of the occupant protection measure.
In addition, the use of the precrash severity indicator as an abstract variable allows the sensor and the actuator of the precrash safety system to be uncoupled, so that it is easier to integrate additional input and/or output signals into the system. As a result, the precrash safety system can be easily expanded.
Preferably, the filtering of the precrash severity indicators is carried out by means of a countdown timer. In this case a countdown timer is set preferably to a predefined value upon occurrence of the (earliest) precrash severity indicator. The occurrence of the precrash severity indicator also causes the countdown timer to start running (for example, the countdown timer starts to run at the time that the set precrash severity indicator ends). Then the countdown timer runs from the predefined value in the direction of an end value (for example, the value 0). As long as the countdown timer is running, all precrash severity indicators having an equally high or lower priority are preferably suppressed. However, the countdown timer is preferably reset (thus, set to the starting value), when a precrash severity indicator having an equally high or lower priority than the priority of the previous precrash severity indicator occurs before the end value is reached.
A second aspect of the invention relates to a device for controlling at least one reversible occupant protection measure of a precrash safety system. In this case the features of the device according to the invention correspond in essence to the features of the above-described method according to the first aspect of the invention. The device according to the invention receives a plurality of input signals, from which a potential risk of an accident can be derived. The device maps the plurality of input signals to precrash severity indicators. The result is that each precrash severity indicator indicates an expected probability and/or severity of the accident. Furthermore, the precrash severity indicators have different priorities and are set as a function of the input signals. Furthermore, the device filters the precrash severity indicators in such a way that upon occurrence of a precrash severity indicator, a subsequent precrash severity indicator is suppressed for a period of time. The at least one reversible occupant protection measure can be actuated as a function of the filtered precrash severity indicators.
The above descriptions of the method and the advantageous embodiments of the method according to the invention also apply correspondingly to the control device according to the invention.
A third aspect of the invention relates to a method for controlling a reversible seat belt tensioner (for example, an electric motor-operated seat belt retractor) of a motor vehicle. According to the method, one or more input signals are received, whereby the input signals indicate a potential risk of an accident. In this respect see the above statements that have already been made within the scope of the description of the first aspect of the invention. The belt tensioner is triggered, when a first input signal of one or more input signals indicates a higher risk of an accident. Then a repeated triggering of the belt tensioner is suppressed for a certain period of time when an input signal—for example, a first input signal—indicates once again a higher risk of an accident.
The method according to the invention prevents the belt tensioner from being triggered multiple times.
As, however, described above with respect to the first aspect of the invention, the suppression does not occur preferably in every case, but rather only for input signals with a correspondingly low priority. For this purpose the plurality of input signals are assigned preferably different priorities. This assignment can also be implemented, for example, indirectly by assigning different precrash severity indicators to the input signals. In this case a repeated triggering of the belt tensioner is suppressed when an input signal, which is assigned an equally high or lower priority than the assigned priority of the first input signal, indicates a higher risk of an accident.
The suppression of a repeated triggering of the belt tensioner is carried out, for example, by use of a countdown timer. The triggering of the belt tensioner initiates, for example, the start of the countdown timer from a starting value in the direction of an end value (for example, 0). As long as the countdown timer is running, a renewed triggering of the belt tensioner is suppressed (at least in the case of the input signals that have the same or a lower priority than the input signal that has generated the earlier triggering action). The countdown timer is preferably reset, when a corresponding input signal having an equally high or lower priority than the priority of the input signal that has generated the earlier triggering action occurs before the end value is reached.
The above descriptions of the method according to the first aspect of the invention and the advantageous embodiments of this method also apply correspondingly to the inventive method according to the third aspect of the invention.
Furthermore, the invention also relates to a control device that is intended for controlling a belt tensioner and that works according to the method according to the third aspect of the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.